Arroyo had some issues throwing Saturday, but said he felt much better Sunday. He's been dealing with a back injury during camp. He said he believes he can still be ready for opening day.
Arroyo posted a 3.79 ERA in 202 innings last year.
"I think he's taking quality at-bats," Porter said, per MLB.com. "The one thing in which Jon and I talked about and [hitting coach John Mallee] is going to get with him today -- he doesn't have to over-swing. You're talking about a guy with tremendous power and he has power to all fields. When you [try] to hit the 500-foot home run instead of hitting the ball hard, sometimes you can miss pitches that you probably could hit.
"Overall, I think his at-bats have been good. I think he's over-swinging right now, trying to make something happen."
After sitting out the 2013 season,
"He's not pitching like a guy who didn't pitch for a year. He looks very much like the guy in Toronto, and Houston a couple of years ago. He's made necessary adjustments. He now uses an assortment of pitches rather than just rely on velocity," manager John Farrell said, per The Boston Globe.
If that goes well, there's a chance Greinke will be able to throw in a game later in the week. Greinke has been dealing with a calf injury, but it's not considered to be serious. He won't pitch in the club's Australian series, but could return early in the season.
Greinke posted a 2.63 ERA in 177 2/3 innings last year.
The news was expected, especially after Zack Greinke's calf injury took him out of consideration for the start. There was a report Thursday that the two pitchers were tabbed to start, but the team waited until Sunday to make the official announcement.
Kemp has shown improvement recently, and is getting closer to game action. Kemp has been limited by an ankle injury during spring. He hit .270/.328/.395 in 263 at-bats last year.
"He brings a different element," said Antony, who noted Mastroianni is a big stolen-base threat.